How to get input file name as column in AWS Athena external tables

Question

I have external tables created in AWS Athena to query S3 data, however, the location path has 1000+ files. So I need the corresponding filename of the record to be displayed as a column in the table.

select file_name , col1 from table where file_name = "test20170516"

In short, I need to know INPUT__FILE__NAME(hive) equivalent in AWS Athena Presto or any other ways to achieve the same.

Answer 1

You can do this with the $path pseudo column.

select "$path" from table

Answer 2

If you need just the filename, you can extract it with regeexp_extract().

To use it in Athena on the "$path" you can do something like this:

SELECT regexp_extract("$path", '[^/]+$') AS filename from table;

If you need the filename without the extension, you can do:

SELECT regexp_extract("$path", '[ \w-]+?(?=\.)') AS filename_without_extension from table;

Here is the documentation on Presto Regular Expression Functions